Retrievable piston advance jet bits



1 a \/Q "3 J INVENTORS ERA/E574 MOQ/ RETRIEVABLE PISTON ADVANCE JET BITS June 25, 1968 e40; ush/1,405

United States Patent 0 3,389,759 RETRIEVABLE PISTUN ADVANCE JET BITS Ernest A. Mori, Glenshaw, and Paul W. Schaul), Verona,

Pa., assignors to Gulf Research 81 Development Company, Pittsburgh, Pa., a corporation of Delaware Filed Nov. 16, 1966, Ser. No. 594,899 7 Claims. (Cl. 175-258) ABSTRACT OF THE DTSCLOSURE A retrievable bit for drilling wells by means of highvelocity streams of abrasive-laden liquid in which a nozzle holder which can be pumped down drill pipe engages an inwardly extending shoulder at the lower end of the drill pipe to hold the nozzle holder within the drill pipe. Outwardly slanting nozzle wells in the nozzle holder receive nozzles which are held in an upper withdrawn posi-' tion by resilient means. When the abrasive-laden liquid is pumped down the drill pipe during the drilling operation, the nozzles are forced down into the wells to direct abrasive-laden liquid against the bottom of a borehole at a distance from the center of rotation of the drill bit to cut a borehole of larger diameter than the drill pipe.

This invention relates to an apparatus for hydraulically jet drilling a well.

A recent development for drilling formations is to utilize abrasive-laden liquid as a drilling fluid and bombard the bottom of the borehole with this liquid by passing it through nozzles at extremely high velocities of at least 500 feet per second. In the operation of heretofore employed jet bits the outlet of the nozzles is maintained within a close and carefully controlled distance from the bottom of the borehole to prevent dissipation of the impact energy in the velocity stream of abrasive-laden liquid discharged from the nozzle and to reduce erosion at the bit by back splash of the abrasive-laden liquid against the bottom of the bit. The drill string is rotated to rotate the bit and cause the exit points of the highvelocity streams to travel over the bottom of the borehole to cut a borehole of the desired diameter. Drilling liquid downwardly discharged from the nozzles cut, substantially by impact, overlapping or contiguous grooves. Virtually the entire removal of rock from the bottom of the hole is thereby accomplished by the initial bombardment by the streams of drilling liquid.

Other jet bits have been designed whose nozzles cut a plurality of concentric vertical grooves separated by intervening annular ridges. The proper interval of separation between a nozzle outlet and the formation is maintained by standoff bars mounted on the bottom of the jet bit. The leading edge of the standoff bars is employed to mechanically break the intervening ridges.

These heretofore employed bits are ineflicient owing to the necessity of pulling the drill pipe in order to change worn or damaged bits. During the replacement of these bits, the fluid within the borehole is quiescent. This may cause the formations adjacent the borehole to cave in and slough owing to the soaking action and the extended periods of time during which the borehole is subjected to a reduced back pressure.

This invention resides in an improved hydraulic jet drilling apparatus in which a series of piston advance kerf cutting nozzles are adapted to direct fluid outwardly against the bottom of the borehole to cut a groove whose outer diameter is substantially the diameter of the borehole. A plurality of stationary jets are directed to cut overlapping annular grooves and remove the matrix not cut by the piston advance jets. Springs located within the piston wells of the piston advance nozzles cause the nozzle to retract into the nozzle holder and permit the 3,38%,759 Patented June 25, 1968 nozzle holder to be recovered at the surface without pulling the drill pipe.

In the drawings:

FIGURE 1 is a diagrammatic View in vertical section showing the jet bit of this invention.

FIGURE 2 is a top view of a nozzle holder suitable for use in the jet bit of this invention.

Referring to FIGURE 1, drill pipe 2 extending from the surface of the earth is attached to the hollow bit body 4 of this invention. A bit shoulder 6 is concentrically formed on the bottom of the inner surface of the bit body 4 to form a seat for the nozzle holder 8 positioned within the bit body 4. An outwardly extending nozzle holder seat 10 is formed on the outer periphery of the nozzle holder 8 to contact the bit shoulder 6 and form a fluid seal thereby causing fluid pumped through the bit body 4 to be directed through the nozzles of the nozzle holder. A nozzle holder relief 12 is outwardly formed on the inner surface of the bit body to facilitate unseating the nozzle holding prior to its removal.

A plurality of downwardly and outwardly directed piston wells 14 are formed through the nozzle holder 8. Nozzle pistons 16, with an O-ring 18 mounted on their outer periphery to effect a fluid seal, are inserted into the piston wells 14. A nozzle insert 20 is installed within the nozzle pistons 16. The nozzle pistons 16 are held in a retracted position by helical piston springs 22 when no pressure is applied to the nozzle pistons 16. As pressure is applied to the nozzle pistons 16 they will extend through the piston well 14.

A fishing neck 26 is mounted on the top center of the nozzle holder 8 to provide a method of removing the nozzle holder 8 without pulling the drill pipe 2. Radially extending standoff bars 28, preferably formed of tungsten carbide, are mounted on the bottom of the nozzle holder 8 to maintain proper nozzle standoff distance between the nozzles and the bottom of the borehole. A hard abrasive-resistant material, such as tungsten carbide, is mounted on the bottom surfaces of the bit body 4 and the nozzle holder 8 to form back splash protectors 30. These back splash protectors 30 prevent erosion of the bit during drilling operations.

Referring to FIGURE 2, a plurality of outwardly di-' rected piston wells 14 are formed through the nozzle holder 8. Nozzle pistons 16 with nozzle inserts 20, preferably to inch in diameter, are inserted into the piston wells 14. A plurality of stationary nozzles 32 with nozzle inserts 20, preferably to inch in diameter, are formed through the nozzle holder 8 and directed to out overlapping grooves and remove the matrix between the groove cut by the piston advance kerf cutting nozzles and the center of rotation of the bit. it is preferred that some of the stationary nozzles are inclined from the vertical to assure complete removal of the rock.

in the operation of this bit the nozzle holder is seated within the bit body. The bit is lowered to the bottom of the borehole on drill pipe extending from the surface of the earth and attached on its lower end to the bit of this invention. As the bit is rotated a ferrous abrasiveladen liquid, such as an invert emulsion of diesel oil and water with entrained ferrous particles or other suitable hydraulic jet drilling fluids, is pumped down the drill pipe and through the bit body. As the fluid passes through the nozzles a differential pressure of approximately 2000 psi. will be maintained across the nozzle holder which will prevent the nozzle body from rotating within the bit body and will cause the drilling liquid to be discharged from the nozzles at extremely high velocities of at least 500 feet per second. This pressure exerted on the top of nozzle pistons will cause the nozzle pistons to advance outwardly to a proper standoff distance, between the discharge end of the nozzle inserts and the borehole of the a well, which will allow the cutting of a groove whose outer diameter is substantially the diameter of the borehole. The portion of the abrasive-laden liquid discharged from the stationary nozzles will cut overlapping grooves and remove the matrix between the groove cut by piston advance lzerf cutting nozzles and the center of rotation of the bit. The standoff bars mounted on the bottom of the nozzle holder will operate to maintain the proper standoff distance between the discharge end of the nozzle inserts and the bottom of the borehole.

As the nozzle inserts become worn or in the event the nozzle holder is damaged, the nozzle holder may be removed from the bit without pulling the drill pipe. To remove a nozzle holder from the bit a wire line with an overshot attached to its lower end is run into the well and latched onto the fishing neck of the nozzle holder. The bit will then be urged against the bottom of the borehole which will force the nozzle holder upward in the bit body and past the nozzle holder relief. The nozzle holder may then be easily withdrawn from the well by the Wire line.

A replacement nozzle holder may be installed by either placing the nozzle holder in the drill pipe at the surface and pumping it downward to seat in the bit body or by running the nozzle holder on a wire line and releasing it.

The hydraulic jet drilling of wells may be accomplished with a bit of this design without removing the drill pipe from the Well. To drill a well without pulling the drill pipe will reduce the danger of formation sloughing and caving. To forego the necessity of pulling the drill pipe to replace worn nozzles will also represent a considerable savings of rig time, supervision and wear of equipment.

Therefore we claim:

1. In apparatus for the hydraulic jet drilling of wells by discharging suspensions of abrasive particles in liquids at a high velocity against the bottom of the borehole, said apparatus having a drill bit body, a bit shoulder formed on the bit body, a retrievable nozzle holder, a nozzle holder seat formed on the nozzle holder and adapted to seat on the bit shoulder and close the lower end of the drill bit body, the improvement comprising a piston Well formed downwardly and outwardly through the nozzle holder, a nozzle slidable in the piston well from an upper retracted position to a lower position at which the nozzle extends beyond the nozzle holder, and resilient means urging the nozzle to the upper position.

2. An apparatus for the hydraulic jet drilling of wells by discharging suspensions of abrasive particles in liquids from retrievable nozzles at a high velocity against the bottom of the borehole comprising a hollow drill bit body, a bit shoulder formed on the inner surface of the bit body, a retr-ievable nozzle holder seated on the bit shoulder, a piston Well formed downwardly and outwardly through the nozzle holder, a nozzle slidable in the piston well from an upper retracted position to a lower position at which the nozzle extends beyond the nozzle holder, a resilient means urging the nozzle to the upper position, a plurality of stationary nozzles extending through the nozzle holder, and a standoff bar mounted on the nozzle holder.

3. An apparatus for the hydraulic jet drilling of wells by discharging suspensions of abrasive particles in liquids from retrievable nozzles at a high velocity against the bottom of the borehole comprising a hollow drill bit body, a bit shoulder formed on the inner surface of the bit body, a retrievable nozzle holder seated on the bit shoulder, a series of piston wells formed downwardly and outwardly through the nozzle holder, a nozzle slidable in each of the piston wells from an upper position to a lower position at which the nozzle extends beyond the nozzle holder for cutting a groove whose outer diameter is substantially the same as the diameter of the borehole, a resilient means urging the nozzle in each of the piston wells to the upper position, a plurality of stationary nozzles extending through the nozzle holder for cutting the bottom of the borehole between the center of rotation of the bit and the groove cut by the series of slidable nozzles, and a standoff bar mounted on the bit body.

4. An apparatus as set forth in claim 3 in which the slidable nozzles extend to a position below the drill bit body and laterally beyond the nozzle holder.

5. An apparatus as set forth in claim 3 in which the nozzles have nozzle inserts of hard abrasive resistant material installed therethrough.

6. An apparatus as set forth in claim 3 in which the nozzles have a discharge diameter of to /1 inch.

7. An apparatus as set forth in claim 3 in which the nozzle body may be removed from the Well without pulling the drill pipe.

References Cited UNITED STATES PATENTS 2,212,491 8/ 1940 Appleby 422 2,963,102 12/1960 Smith 175-422 3,101,799 8/1963 Grabow 175422 JAMES A. LEPPINK, Primary Examiner. 

